I was watching Meinrad Abbey's stream of 1st Vespers of John the Baptist, and couldn't make out most of the words to whichever translation of Ut queant laxis they seem to be using. Could anyone point me to this text? Unless my hunch is right that it's an in-house text and not otherwise published.

If it helps, the first line seems to be something like "The speechless message Gabriel has spoken" but I can't make out much more than that.